Advanced granular-type perpendicular recording media

Takahashi, M.; Saito, Shin

doi:10.1016/j.jmmm.2008.07.039

Cited by 16 publications

(11 citation statements)

References 11 publications

(10 reference statements)

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“…As an argument it is mentioned that high density recording requires superior field gradients, which only can be realized very close to the pole tip. As a consequence media Composite media design where proposed with negative anisotropy instead of the soft layer 34 .…”

Section: Open Questionsmentioning

confidence: 99%

Exchange-coupled perpendicular media

Suess

Lee

Fidler

et al. 2009

Journal of Magnetism and Magnetic Materials

115

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The potential of exchange spring bilayers and graded media is reviewed. An analytical model for the optimization of graded media gives an optimal value of the magnetic polarization of J s = 0.8 T. The optimum design allows for thermally stable grains with grain diameters in the order of 3.3 nm, which supports ultra high density up to 5 -10 Tbit/inch².The switching field distribution is significantly reduced in bilayer media and graded media compared to single phase media. For the graded media the switching field distribution is reduced by about a factor of two. For bilayer media the minimum switching field distribution is obtained for soft layer anisotropies about 1/5 of the hard layer anisotropy. The influence of precessional switching on the reversal time and the reversal field is investigated in detail for magnetic bilayers. Exchange spring bilayers can be reversed with field pulses of 20 ps.

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Section: Open Questionsmentioning

confidence: 99%

Exchange-coupled perpendicular media

Suess

Lee

Fidler

et al. 2009

Journal of Magnetism and Magnetic Materials

115

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“…However, there are few reports on the structural analysis of films including ordered phases by taking into account the stacking sequence of close-packed plane [7,8,10]. The stacking sequence of Co-based alloy film is influenced by the substrate or underlayer material [11]. Ru has been used as an underlayer to prepare Co-Pt-Cr films with hcpbased disordered A3 structure [11,12].…”

Section: Introductionmentioning

confidence: 99%

“…The stacking sequence of Co-based alloy film is influenced by the substrate or underlayer material [11]. Ru has been used as an underlayer to prepare Co-Pt-Cr films with hcpbased disordered A3 structure [11,12]. Ru is also expected to stabilize the hcp-based structure for CoPt films.…”

Section: Introductionmentioning

confidence: 99%

Structure analysis of CoPt alloy film with metastable ordered phases ofL1₁andB_hformed on Ru(0001) underlayer

Ohtake

Suzuki

Kirino

et al. 2014

EPJ Web of Conferences

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Abstract. CoPt alloy films of 40 nm thickness are prepared on MgO(111) substrates with and without Ru(0001) underlayer at 300 °C by radio-frequency magnetron sputtering. CoPt films with the close-packed plane parallel to the substrate surface grow epitaxially on the Ru underlayer as well as on the MgO substrate. Flat surfaces with the arithmetical mean roughness value of 0.2 nm are realized for both films. The crystal structure is determined by considering the atomic stacking sequence of close-packed plane and the order degree. The film formed on MgO substrate consists of an fcc-based L1 1 ordered crystal, whereas the film grown on Ru underlayer involves an hcp-based B h ordered crystal in addition to the L1 1 ordered crystal. The order degrees of films formed on MgO substrate and Ru underlayer are 0.30 and 0.34, respectively. The L1 1 crystal consists of two variants whose stacking sequences of close-packed plane are ABCABC… and ACBACB…, while the B h crystal is a single-crystal with the stacking sequence of ABAB… Formation of B h crystal is promoted on the Ru underlayer. The film formed on Ru underlayer shows a strong perpendicular magnetic anisotropy reflecting the magnetocrystalline anisotropies of L1 1 and B h crystals.

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“…1),2) A positive-/ negative-Ku exchange coupled recording media decrease the switching field through the local spin twisted structure. 3),4) The field generation layer (FGL) of a spin torque oscillator with negative Ku can realize high oscillation frequency because the magnetization of FGL becomes stable in the plane direction. 5), 6) As for the materials, '-Fe-C, 7) dhcp-CoFe, 8) NiAs-type Mn50Sb50, 9) and disordered hcp-CoIr 10) are all known to exhibit negative Ku at room temperature (RT).…”

Section: Introductionmentioning

confidence: 99%

Atomic layer stacking structure and negative uniaxial magnetocrystalline anisotropy of Co100^|^minus;xIrx sputtered films

et al. 2013

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The negative uniaxial magnetocrystalline anisotropy (Ku) was evaluated for various compositions of Co100-xIrx thin films with respect to the atomic layer stacking structure. Pure Co film fabricated at a substrate temperature (Tsub) of 600 C was found to have a positive Ku of 6.1×10 6 erg/cm 3 . With increasing x, the sign of Ku changed from positive to negative, and the negative Ku took a maximum value of -9.6×10 6 erg/cm 3 at around x = 20 at. % for films fabricated at Tsub = 600 C. Adding more Ir decreased the absolute value of the negative Ku which became 0 over x = 50 at. %. X-ray diffraction analysis and scanning transmission electron microscopy revealed that the atomic layer stacking structure of the Co100-xIrx films changed from -A-B-A-B-(hcp) to -A-B-C-A-B-C-(fcc) stacking with increasing Ir content. Moreover, Co80Ir20 grains were revealed to consist of 2 kinds of randomly located composition-modulated atomic layers, nearly pure-Co and pure-Ir layers, while Co and Co50Ir50 had disordered structures. In this paper, a new perspective on the atomic layered structure with superlattice diffraction, which is different from the conventional "ordered structure", is discussed.

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Advanced granular-type perpendicular recording media

Cited by 16 publications

References 11 publications

Exchange-coupled perpendicular media

Exchange-coupled perpendicular media

Structure analysis of CoPt alloy film with metastable ordered phases ofL1₁andB_hformed on Ru(0001) underlayer

Atomic layer stacking structure and negative uniaxial magnetocrystalline anisotropy of Co100^|^minus;xIrx sputtered films

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Advanced granular-type perpendicular recording media

Cited by 16 publications

References 11 publications

Exchange-coupled perpendicular media

Exchange-coupled perpendicular media

Structure analysis of CoPt alloy film with metastable ordered phases ofL11andBhformed on Ru(0001) underlayer

Atomic layer stacking structure and negative uniaxial magnetocrystalline anisotropy of Co100^|^minus;xIrx sputtered films

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Structure analysis of CoPt alloy film with metastable ordered phases ofL1₁andB_hformed on Ru(0001) underlayer